The invention relates to electrotechnology area, and in particular, to production of secondary solid-state current sources (storage batteries).
The invention proposes the method for production of safe solid-state batteries with high energy capacity and includes the following steps:
Ensuring contact between a current collector, a solid anode, a solid electrolyte, a solid cathode, and one more current collector in the mentioned order. At that, the reversible solid-phase fluorination/defluorination processes occur at both the cathode and the anode, and the electrolyte has the high fluoride-ion conductivity along with the low electronic conductivity in the solid phase.
Baking a current source consisting of the current collector, the anode, the electrolyte, the cathode and the current collector by means of baking and thermoelectric influence.
According to the present invention, “the current source” is both a separate galvanic cell consisting of the current collector, the anode, the electrolyte, the cathode and the other current collector, connected in the mentioned order and a battery, consisting of several galvanic cells, connected in parallel or in series.
In their composition anode, electrolyte, and cathode in the presented method of production of solid-state secondary current source with high specific energy capacity can correspond to composition of the current source from application RF Patent No 2005111722, issued on 21 Apr. 2005, wherein
The anode is a metal (or its alloy) selected from the group consisting of Li, K, Na, Sr, Ba, Ca, Mg, Al, Ce, La or their alloys, or from the alloys of the listed metals with the metals, selected from the group of Pb, Cu, Bi, Cd, Zn, Co, Ni, Cr, Sn, Sb, Fe; and in the charged state the anode consists of the fluorides of the aforementioned metals, correspondingly.
In the charged state the cathode is made from the simple fluorides, such as MnF2, MnF3, TaF5, NdF5, VF3, VF5, CuF, CuF2, AgF, AgF2, BiF3, PbF2, PbF4, CdF2, ZnF2, CoF2, CoF3, NiF2, CrF2, CrF3, CrF5, GaF3, InF2, InF3, GeF2, SnF2, SnF4, SbF3, MoF5, WF5, fluorinated black lead or the alloys based on them, or their mixtures; and in the discharged state it can be made from the metal selected from the group of Mn, Ta, Nd, VF, Cu, Ag, Bi, Pb, Cd, Zn, Co, Ni, Cr, Ga, In, Ge, Sn, Sb, Mo, W, black lead, or the listed metal alloys, or the mixture.
The solid-state electrolyte can be made from either the fluorides of La, Ce or the compound fluorides based on them together with an alloying additives, such as fluoride/fluorides of alkaline-earth metals (CaF2, SrF2, BaF2) and/or fluorides of alkaline metals (LiF, KF, NaF) and/or alkaline metal chlorides (LiCl, KCl, NaCl); or the compound fluorides based on the alkaline-earth metal fluorides (CaF2, SrF2, BaF2) with an alloying additives of the rare-earth metal fluorides or/and the alkaline metal fluorides (LiF, KF, NaF); and (or) the chlorides of alkaline metals (LiCl, KCl, NaCl); or the compound fluorides based on PbF2 containing SrF2, or BaF2, or CaF2, or SnF2 along with KF additive; or the compound fluorides based on BiF3 containing SrF2, or BaF2, or CaF2, or SnF2 along with KF additive; and the anode, the electrolyte and the cathode contain component or components that prevent destruction of a solid-state battery during charge/discharge cycles.
RF Patent No 2136083, HO1M6/18 (Informational Bulletin No 24, 1999) discloses the method for production of solid-state fluoride ion galvanic cells in the form of the multilayer structures using the technique of layer-by-layer pressing of the powders of the anodic, cathodic and electrolyte materials.
The drawback of the given method is that by using original solid ionic conductors with sufficiently high level of conductivity, resistance inside the produced current sources increases 100 and more times compare to resistance of the solid ionic conductors materials. This is associated with very high resistance at the particles' interface of the pressed structures (in particular of the electrolyte material) consisting of the powders of the solid-state ionic conductors. This is the widely known data for the polycrystalline structures made from the powders of the ionic conductors using pressing method (A. K. Ivanov-Shitz, I. V. Murin//Ionica of solid state, v.1., St. Petersburg University, 2000, pp 73-74).
At that, both the anode/electrolyte and the cathode/electrolyte interfaces have the high resistance, too. These resistances substantially determine the high internal resistance of the solid-state current sources produced by this technique. In that case the discharge power of the current sources at 25 C is measured in microwatts. This fact essentially limits the application area of the batteries.
The method, which is the closest to this invention, is disclosed in RF Patent No 1106382, H01M 6/18, issued on 10 Oct. 1999. According to the method the chemical battery is made by coating both sides of solid electrolyte with electrode pastes that have different polarity. Then, the stack is burned under the thermoelectric influence of electric current passing through the electrodes with the voltage that does not exceed the destruction potential of the electrolyte.
The known method of producing the solid-state battery has the following disadvantages:
Coating both sides of solid electrolyte with electrode pastes that have different polarity (anode and cathode) does not allow production of high quality current sources usually because of high chemical activity of anode material. This leads to changes in chemical composition of electrodes that consequently leads to lower quality of production and degradation of characteristics of the current source, specifically increase in internal resistance of the current source, especially during baking at high temperatures.
The method is complex enough because of the special requirements to the battery baking which should be carried out in the inert atmosphere that meets the strict requirements with respect to the content of oxygen, nitrogen and moisture in order to prevent contamination of the electrode materials.
The battery thermoelectric treatment by direct current leads to the sintering of the electrode materials and the electrolyte along with the change in the chemical composition of the electrode materials. As a result, the battery quality deteriorates, and the internal resistance grows.